Police and Bedouins have skirmished frequently over the years. The latest outbreak of violence came after a tribal leader escaped prison in February and rallied a group of armed men. Authorities say the Bedouins run criminal gangs, but the tribesmen say their people have no jobs and have been marginalized for generations.

The Bedouins reportedly have threatened to sabotage oil and gas pipelines, including a natural-gas line that supplies Israel. Egyptian Interior Minister Habib Adli met with Bedouin elders on Tuesday to try to calm tensions.

"The meeting was a failure," Moussa Delhi, a Bedouin leader in Amro Valley in central Sinai, told Agence France-Presse. "Bedouins marched in protest from Amro Valley to other villages to demand improved treatment and the release of detainees. The elders who met the interior minister were appointed by the government and do not represent Bedouins."

Rights groups have blamed the government for years of oppression against the Bedouins. But police say the tribesmen are part of a smuggling network that tunnels supplies into the Gaza Strip and sneaks African migrants across the border into Israel. On Tuesday, Egyptian guards shot and killed an Eritrean woman near a border fence.

Egypt has had trouble keeping order in the Sinai, which is crucial to the nation’s tourism industry. In 2004, twin bombings at resorts in Taba and Ras al-Shitan killed at least 34 people. A year later, 88 people died in bomb attacks in Sharm el Sheikh, and in 2006 at least 23 people were killed in blasts in Dahab. Bedouins have been involved in a number of such attacks.